In 1972 the Auto Industry manufactured 2 million identical Chevy Caprices. Those were the days. Identical is boring for the assembly line worker. I am positive that a typical Caprice auto assembly line assignment of installing the same three bolts on every car going by, would drive me bonkers. As an engineer, it was all about manufacturing speed. 2 million per year works out to one part every 4 seconds for a three shift operation. And God help you if the vehicle needed 8 copies for parts like pistons. Henry Ford would be proud. You can have any color that you want as long as it is black. 1972 was the high water mark for utilizing mass production to reduce manufacturing cost by making only identical copies. The high volume price convinced most buyers to compromise what they wanted. (An Ford F150 pickup truck at 500,00 annual volume is the highest selling model today,but the volume includes two entirely different chassis in that quantity)
Computerized ERP systems increased our ability to manage a degree of variability. This is not enough by itself. In most cases a buyer cannot afford to have most manufactured products custom and designed just for them. The first test Chrysler Minivan that I built cost $1,000,000. This bargain price was only possible because we were building 100 test units. I never have had personal money of this magnitude to spend on having a vehicle designed just for me. In the real market place, it is possible to purchase optional features for those items that are sufficiently popular to have enough buyers to share the design, development and testing cost.
While we were planning the families of options to fit within the Chrysler Minivan family, we built in the ability to make a camper van. To this day there is a split within the Chrysler minivan sheet metal frame behind the front seats to enable creation of a camper vehicle frame. Chrysler Minivan sales have been high enough that they never needed to go after the camper market segment. Other makers such as VW discovered that niche in Europe.
The buyers would like to think that they can custom order whatever they want. The reality is that someone has engineered a family of product so that the buyer can customize within a range of options. Yes, you can choose the flavor of gatoraid that you want but it comes in the same bottle off of the same packaging line